1. Field of the Invention
This invention relates to a driving circuit used for a display device such as a liquid crystal display device.
2. Description of the Related Art
In a liquid crystal display device having crystal cells arranged so as to form a matrix, it is prohibited to apply a voltage having a DC component to a crystal cell in order to prevent the crystal cell from being deteriorated. Therefore, a binary voltage signal received as a display data having a DC component is converted into an AC signal having no DC component by a binary modulating signal having a predetermined period.
Converting the display data into the AC signal is realized by generating a voltage according to logic levels of the display data and the modulating signal.
As long as the display data synchronizes with the modulating signal, there is no problem. However, when a certain phase difference occurs between the display data and the modulating signal, that is, when the display data is asynchronous with the modulating signal, there arises such a problem that a noise appears on an image displayed on a display device as described in detail later.